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United States Patent |
5,143,877
|
Geus
,   et al.
|
September 1, 1992
|
Process for preparation of a catalyst
Abstract
Process for the preparation of one or more metal or metal compounds
containing catalysts or catalyst precursors wherein a complex cyanide of
the general formula M.sub.1 M.sub.2 (CN).sub.p-x(Y).sub.x wherein M.sub.1
represents a cationic moiety comprising one or more metal ions,
NH.sub.4.sup.+ and/or a quaternary ammonium ion, M.sub.2 forms part of the
anionic moiety and represents one or more polyvalent metals, CN represents
a cyanide moiety as defined hereinbefore, Y represents one or more
ligands, p is a number ranging from 2-8, x is a number ranging from 0-4
and p/x is at least 1 when x>0, present on a carrier, is subjected to a
decomposition treatment under oxidative conditions.
The catalysts thus obtained can be suitably applied for instance in the
preparation of hydrocarbons and/or oxygenates from carbon monoxide and
hydrogen and in the hydrodesulphurization of hydrocarbonaceous materials.
Inventors:
|
Geus; John W. (Bilthoven, NL);
Boellaard; Eliza (Breukelen, NL)
|
Assignee:
|
Shell Oil Company (Houston, TX)
|
Appl. No.:
|
668829 |
Filed:
|
March 13, 1991 |
Foreign Application Priority Data
Current U.S. Class: |
502/60; 502/200 |
Intern'l Class: |
B01J 027/26 |
Field of Search: |
502/200,60
|
References Cited
U.S. Patent Documents
4146503 | Mar., 1979 | Vogt et al. | 252/455.
|
4172053 | Nov., 1979 | Vogt et al. | 252/447.
|
4186112 | Jan., 1980 | Vogt et al. | 252/471.
|
4237063 | Dec., 1980 | Bell et al. | 260/449.
|
4347164 | Aug., 1982 | Scherzer | 252/455.
|
4394298 | Jul., 1983 | Nowack et al. | 252/438.
|
4588705 | May., 1986 | Vanderspurt et al. | 502/177.
|
Foreign Patent Documents |
2653986 | Nov., 1976 | DE.
| |
77/7011 | Nov., 1977 | ZA.
| |
Other References
J. of Cat. (71), 111-118 (1981).
|
Primary Examiner: Shine; W. J.
Claims
What is claimed is:
1. A process for the preparation of catalysts or catalyst precursors
containing at least one metal and/or metal compounds wherein a complex
cyanide of the general formula M.sub.1 M.sub.2 (CN).sub.p-x (Y).sub.x
wherein M.sub.1 represents a cationic moiety comprising at least one metal
ion, NH.sub.4.sup.+ or a quarternary ammonium ion; M.sub.2 forms part of
the anionic moiety and represents at least one polyvalent metal, CN
represents a cyanide moiety as defined hereinbefore, Y represents one or
more ligands, p is a number ranging from 2-8, x is a number ranging from
0-4 and p/x is at least 1 when x>0, present on a carrier is subjected to a
decomposition treatment under oxidative conditions.
2. The process according to claim 1, wherein the oxidative treatment is
carried out at a temperature of at least 200.degree. C.
3. The process according to claim 2, wherein the temperature is between
250.degree. C. and 450.degree. C.
4. The process according to claim 1, wherein the decomposition treatment is
carried out in an environment containing at least 0.5% by volume of an
oxidizing agent.
5. The process according to claim 4, wherein use is made of oxygen, ozone
or a hydroperoxide as an oxidizing agent.
6. The process according to claim 5, wherein use is made of diluted air as
an oxidizing agent.
7. The process according to claim 1, wherein use is made of a complex
cyanide wherein M.sub.1 represents one or more transition metal moieties,
a group IVa metal moiety, a group Ia or IIa metal moiety and/or
NH.sub.4.sup.+, a Group Ib or IIB metal moiety, M.sub.2 represents a Group
VIb or Group VIII metal moiety, CN represents cyanide, p represents the
number 4, 6 or 8 and Y represents a NO group when x is not zero.
8. The process according to claim 7, wherein use is made of a complex
cyanide wherein M.sub.1 represents one or more Group VIII metal moieties,
one or more Group IB metal moieties or one or more Group IVa metal
moieties, M.sub.2 represents a Fe, Co, Ni, Mo or W metal moiety, p
represents the number 4, 6 or 8 and x is zero.
9. A process according to claim 8, wherein use is made of a complex cyanide
wherein M.sub.1 represents a Cu, Ni or Co moiety and M.sub.2 represents a
Fe, W or Mo moiety.
10. The process according to claim 1, wherein use is made of a complex
cyanide on a carrier selected from the group consisting of a refractory
oxide, a zeolite or a mixture thereof.
11. The process according to claim 10, wherein use is made of a complex
cyanide applied on a carrier selected from the group consisting of
alumina, silica-alumina, titania, magnesia, a crystalline silicate or
mixtures thereof.
12. The process according to claim 10, wherein use is made of rom 5% to 95%
by weight of carrier, calculated on total weight of dried complex cyanide
and carrier.
13. The process according to claim 12, wherein use is made of from 40% to
90% weight of carrier, calculated on total weight of dried complex cyanide
and carrier.
14. The process according to claim 1, wherein use is made of a complex
cyanide which has been obtained on a carrier by reaction between one or
more metal compounds containing M.sub.1 moieties and a cyanide containing
a M.sub.2 moiety.
15. The process according to claim 1, wherein a carrier material is treated
with one or more cyanides containing a M.sub.2 moiety and after drying is
subjected to impregnation with one or more compounds containing M.sub.1
moieties so as to form the complex cyanide.
16. The process according to claim 1, wherein a carrier material is treated
with one or more compounds containing M.sub.1 moieties and after drying is
subjected to impregnation with one or more cyanides containing a M.sub.2
moiety so as to form the complex cyanide.
17. The process according to claim 15, wherein incipient wetness
impregnation is used to introduce either one or more compounds containing
one or more M.sub.1 moieties or the cyanide containing a M.sub.2 moiety on
the carrier.
18. The process according to claim 1, wherein use is made of a complex
cyanide which has been obtained by treating a carrier with a soluble
complex cyanide and drying the thus treated carrier.
19. The process according to claim 1, wherein the oxidative decomposition
treatment is followed by an activating treatment under reducing
conditions.
20. The process according to claim 19, wherein the activating treatment is
carried out in the presence of hydrogen at a temperature up to 500.degree.
C. and at a pressure of up to 10 MPa.
21. The process according to claim 20, wherein the reducing treatment is
carried out at a temperature in the range between 50.degree. C. and
300.degree. C.
Description
BACKGROUND OF THE INVENTION
The present invention relates to the preparation of one or more metal
and/or metal compounds containing catalysts or catalyst precursors
starting from complex cyanides. The present invention also relates to the
use of catalysts obtained from cyanide complexes in the production of
hydrocarbons from carbon monoxide and hydrogen as well as in the
hydrodesulphurisation of hydrocarbonaceous materials.
One of the problems often encountered in the manufacture of
metal-containing heterogeneous catalysts is the phenomenon of reaction of
the metal ion(s) to be incorporated on the carrier with the carrier. This
can already happen during the initial contact of the metal ion(s) to be
incorporated on the carrier and is many times observed when subjecting the
appropriate metal ion(s) containing carrier to a customary thermal
treatment which is normally used to transfer the system into the
catalytically desired species or to stabilise the system obtained or both.
In particular, it is a well-known problem for iron and/or manganese
containing catalyst, but also nickel and cobalt containing catalysts are
difficult to manufacture because of this unwanted tendency of metal
ion/support interaction.
It should be noted that complex cyanides can be used as starting materials
in the preparation of supported catalysts by firstly introducing an
appropriate cyanide to a support, or alternatively precipitating a complex
cyanide on a support iron a metal salt and an appropriate cyanide followed
by activating the cyanide thus introduced. For instance, in U.S. Pat.
specification 4,186,112 a process is described for reducing carbon
monoxide by means of hydrogen using supported catalysts prepared by
precipitating a polymetal salt of a hydrocyanic acid which is subjected to
a so-called forming step, after separating and drying the precipitated
salt. It is reported that forming takes place when thermally decomposing
the salt in contact with hydrogen or a mixture of hydrogen and carbon
monoxide. It is also possible to carry out the thermal decomposition under
vacuum.
It is further known (J. of Cat. 71], 111-118 1981]) to produce finely
dispersed metals in zeolites by reacting a metal-exchanged zeolite and an
anionic, metal-containing coordination compound, specifically a
water-soluble, metal cyanide complex followed by subsequent reduction with
hydrogen at a temperature of 400.degree. C.
It has now surprisingly been found that very interesting catalysts or
catalyst precursors can be obtained which do not suffer (or only to a
marginal extent) from unwanted metal ion/support interaction when complex
cyanide containing carriers are subjected to a decomposition treatment
under oxidative conditions. In general, it has been found that, especially
after an activation step, more active and more stable catalysts will be
obtained.
SUMMARY OF THE INVENTION
The present invention thus relates to a process for the preparation of one
or more metal and/or metal compounds containing catalysts or catalyst
precursors wherein a complex cyanide of the general formula M.sub.1
M.sub.2 (CN.sub.p-x (Y).sub.x wherein M.sub.1 represents a cationic moiety
comprising one or more metal ions, NH.sub.4.sup.+ and/or a quaternary
ammonium ion, M.sub.2 forms parts of the anionic moiety and represents one
or more polyvalent metals, CN represents a cyanide moiety as defined
hereinafter, Y represents one or more ligands, p is a number ranging from
2-8, x is a number ranging from 0-4, and p/x is at least 1 when x>0,
present on a carrier is subjected to a decomposition treatment under
oxidative conditions.
The present invention further relates to a process for the preparation of
hydrocarbons and/or oxygenates by contacting carbon monoxide and hydrogen
with a catalyst according to the invention.
The invention still further relates to a process for the
hydrodesulphurisation of hydrocarbonaceous materials by contacting such
materials in the presence of hydrogen at elevated temperatures and
pressures with a catalyst according to the invention.
The invention also relates to a process of the production of ethylene oxide
and/or ethylene glycol by using silver catalysts obtained from a complex
cyanide which has been subjected to decomposition treatment according to
the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a graphical representation of the decomposition of copper/iron
complex cyanide with part c under oxidative conditions according to the
invention and parts a and b, not under oxidative conditions, for
comparison.
FIG. 2 is a graphical representation of hydrogen consumption of a
copper/iron catalyst according to the invention.
DESCRIPTION OF PREFERRED EMBODIMENTS
The decomposition treatment under oxidative conditions to be specified
hereinafter can be suitably carried out at a temperature of at least
200.degree. C. Preference is given to a temperature between 250.degree. C.
and 450.degree. C. The optimum temperature to be applied depends to some
extent on the type and number of metal moieties present in the complex
cyanide containing carrier.
Suitably the decomposition treatment is carried out in an environment
containing at least 0.5% by volume of an oxidising agent. It is also
possible, and in fact preferred to use an environment containing a larger
amount of oxidising agent. Preference is given to the use of (diluted) air
as oxidising agent
Examples of oxidising agents comprise oxygen, ozone and hydroperoxides. The
environment containing the oxidative agent normally comprises an inert
medium, such as an inert gaseous compound such as nitrogen, argon or
helium. Preferably, air is used to perform the decomposition treatment in
accordance with the present invention.
The complex cyanide containing carrier is suitably subjected to the
decomposition treatment according to the present invention when present in
a closed vessel with venting facilities such as an autoclave or a rotating
kiln.
Complex cyanides present on carriers which can be subjected to the
decomposition process in accordance with the present invention can be
represented by the general formula M.sub.1 M.sub.2 (CN).sub.p-x (Y).sub.x
wherein M.sub.1 and M.sub.2 are as defined hereinbefore. It is possible
that some interchange may take place between moieties M.sub.1 and M.sub.2
during the formation of the complex cyanides. It is also possible that
part of the M.sub.1 moiety is replaced by H.sup.+, e.g. by means of an
ion-exchange procedure. When M.sub.1 represents a quaternary ammonium ion
preference is given to the lower quaternary alkyl ammonium ions such as
tetramethyl. tetraethyl and dimethyl diethyl ammonium ions. The presence
of quaternary ammonium ions may have an advantageous effect when
non-aqueous impregnation methods are envisaged.
The expression "a cyanide moiety" as used throughout the present
specification is meant to include apart from the cyano group (the cyanide
group proper) also the isocyano group, the thiocyano group, the
isothiocyano group, the cyanato group and the isocyanato group. Preference
is given to the presence of the cyanide group proper in the complex
cyanide structure.
Depending on the coordinative preferences of the (various) metal(s) present
in the complex cyanide, the number for p can range from 2-8. Also the
number of Y moieties present has a bearing on the value for p. Preferably,
p represents an even number in particular 4, 6 or 8. For complex cyanides
having M.sub.2 representing palladium, p is equal to 4, for complex
cyanides having M.sub.2 representing iron, p is equal to 6 and for complex
cyanides having M.sub.2 representing molybdenum, p is equal to 8.
The Y moiety suitably represents one or more of NO, CO, NH.sub.3, NO.sup.+
or NO.sub.2.sup.-. Suitably Y represents one or more NO moieties. Suitably
up to four ligands Y can be present in the complex cyanides provided that
the ratio p/x is at least 1 when x.times.0. Preference is given to complex
cyanides containing not more than 2 and in particular no ligands Y.
Without wishing to be bound to any particular theory it should be noted
that the surprising activity and performance of catalysts produced in
accordance with the decomposition treatment under oxidative conditions may
be related to the observation that water present in the complex cyanides
when precipitated on the appropriate carrier is preferentially removed
prior to the decomposition treatment according to the present invention.
When the cyanide group is decomposed in the substantial absence of water
apparently a decomposition mechanism applies which substantially prevents
the unwanted interaction between the metal(s) remaining on the carrier and
the sites on the carrier normally exposed to undergo metal/site
interaction.
The process according to the present invention is suitably carried out by
using a complex cyanide wherein M.sub.1 represents one or more transition
metal moieties, a Group IVa metal moiety, a Group Ia or IIa metal moiety
and/or NH.sub.4.sup.+, a Group Ib or IIb metal moiety, M.sub.2 represents
a Group VIb or Group VIII metal moiety, CN represents cyanide, p
represents 4, 6 or 8 and Y represents a NO group when x is not zero.
Preferably, the process according to the present invention is carried out
by using a complex cyanide wherein M.sub.1 represents one or more Group
VIII, one or more Group Ib or one or more Group IVa metal moieties,
M.sub.2 represents a Fe, Co, Ni, Mo or W metal moiety, p represents 4, 6
or 8 and x is zero. In particular, use is made of a complex cyanide
wherein M represents a Cu, Ni or Co moiety and M.sub.2 represents a Fe, W
or Mo moiety.
As regards the various Groups of the Periodic Table of the Elements
reference is made to the Handbook of Chemistry and Physics, 64th Edition,
1983 published by the Chemical Rubber Company.
Examples of complex cyanides which can be used (after having been
incorporated on a carrier) as starting materials in the decomposition
treatment in accordance with the present invention comprise Cu.sub.2
Fe(II)(CN).sub.6, Fe.sub.2 Fe(II)(CN).sub.6, Ni.sub.2 Fe(II)(CN).sub.6,
Ag.sub.4 Fe(II)(CN).sub.6, CuFe(II)(CN).sub.5 (NO), FePd(CN).sub.4,
Cu.sub.3 [Fe(III)(CN).sub.6 ].sub.2, Co.sub.3 [Fe(III)(CN).sub.6 ].sub.2,
Cu.sub.2 Mo(CN).sub.8, Co.sub.2 Mo(CN).sub.8, CuNiFe(CN).sub.6 and
Mn.sub.2 Fe(II)(CN).sub.6. Normally, the complex cyanides will contain
water of hydration.
Suitably, refractory oxides as well as zeolites and mixtures thereof can be
used as carrier for the complex cyanides to be treated according to the
present invention. Examples of suitable refractory oxides comprise
alumina, silica-alumina, titania, magnesia or mixtures of two or more of
such refractory oxides. Good results have been obtained using alumina and
titania as carrier materials. It may be useful to subject the refractory
oxides to an activating treatment prior to the incorporation of the
complex cyanides thereupon.
Crystalline (metallo)silicates can also be used as carrier materials, if
desired together with one or more refractory oxides. Crystalline alumino
silicates are a class of crystalline (metallo) silicates which can be
suitably applied.
Suitably, the process according to the present invention is carried out
using of from 5% to 95% by weight of carrier, calculated on total weight
of dried complex cyanide and carrier. Preference is given to the use of of
from 40% to 90% by weight of carrier, calculated on total weight of dried
complex cyanide and carrier.
The complex cyanides can be suitably incorporated on the appropriate
carrier by in situ formation e.g. by reaction of one or more metal
compounds containing M.sub.1 moieties, in particular one or more salts
containing M.sub.1 moieties, and a cyanide containing a M.sub.2 moiety.
Preferably, the complex cyanides are incorporated on the carrier by
treating the appropriate carrier with one or more cyanides containing a
M.sub.2 moiety followed by drying and subjecting the carrier containing
the cyanide to impregnation with one or more compounds containing M.sub.1
moieties, in particular one or more salts containing M.sub.1 moieties, so
as to form the complex cyanide. It is also preferred to incorporate the
complex cyanides on the appropriate carrier by treating the appropriate
carrier with one or more compounds containing M.sub.1 moieties, in
particular one or more salts containing M.sub.1 moieties, followed by
drying and subjecting the carrier containing the M.sub.1 moiety to
impregnation with one or more cyanides containing a M.sub.2 moiety so as
to form the complex cyanide.
It is also possible to treat an appropriate carrier with a soluble complex
cyanide and drying the thus treated carrier to produce the complex
cyanide(s) containing carrier to be subjected to a decomposition treatment
under oxidative conditions according to the present invention.
It is also possible to use the so-called incipient wetness impregnation
method. Using that method gives the opportunity to introduce either one or
more salts containing one or more M.sub.1 moieties or the cyanide
containing a M.sub.2 moiety on the carrier.
When salts containing one or more M.sub.1 metal moieties and cyanides
containing a M.sub.2 moiety have been introduced on the carrier which
results in the formation of the appropriate complex cyanide(s) the metal
moieties M.sub.1 and M2 are still in non-zero valencies. By subjecting the
complex cyanides to a decomposition treatment under oxidative conditions
it will be clear that the cyanide moieties will be substantially
destructed which will leave the M.sub.1 and M.sub.2 metal moieties
substantially in the appropriate oxidic form.
In the event that it is desired, e.g. for catalytic purposes to have the
metal moieties in substantially the zero valency state it will be
necessary to subject the complex cyanides to a reducing treatment. Such a
treatment which will normally activate or increase the catalytic behaviour
of the catalysts can be carried out suitably in the presence of hydrogen
at a temperature up to 500.degree. C. and at a pressure of up to 10 MPa.
Preferably, the reducing treatment is carried out at a temperature in the
range between 50.degree. C. and 300.degree. C.
The complex cyanides present on a carrier which have been subjected to a
decomposition treatment in accordance with the present invention can be
used, either as such or after a reducing treatment as discussed
hereinbefore, as catalyst precursors or as catalysts in a great many
applications, depending on the character of the metal moieties M.sub.1 and
M.sub.2. Without wishing to be bound to any particular theory it is
thought that the attractive catalytic properties of the catalysts
obtainable from complex cyanides as defined hereinbefore (after at least
the decomposition treatment under oxidative conditions) are related to the
very effective dispersion of the appropriate metal moieties throughout the
system.
The present invention relates in particular to a process for the
preparation of hydrocarbons and/or oxygenates from carbon monoxide and
hydrogen wherein a mixture based on carbon monoxide and hydrogen is
contacted with a catalyst comprising one or more catalytically active
metal components on a support which catalyst has been obtained by
subjecting a complex cyanide according to the general formula M.sub.1
M.sub.2 (CN).sub.p-x (Y).sub.x wherein M.sub.1 represents a cationic
moiety comprising one or more metal ions, NH.sub.4.sup.+ and/or a
quaternary ammonium ion, M.sub.2 forms part of the anionic moiety and
represents one or more polyvalent metals, CN represents a cyanide moiety
as defined hereinbefore, Y represents one or more ligands, p is a number
ranging from 2-8, x is a number ranging from 0-4. and p/x is at least 1
when x>0, present on a carrier to a decomposition treatment under
oxidative conditions.
In particular, catalysts loaded with suitable Fischer-Tropsch metal(s),
e.g. Group VIII metals such as iron, nickel or cobalt, optionally
containing one or more promoters such as zirconia or rhenium, can be
suitably applied in the so-called heavy paraffin synthesis steps in an
integrated process for the manufacture of middle distillates starting from
methane to produce a syngas mixture which serves as starting material for
the heavy paraffin synthesis and wherein the heavy paraffins produced are
subjected to a catalytic heavy paraffin conversion process to produce the
desired middle distillates. It may be advantageous to subject the complex
cyanides which have been subjected to a decomposition treatment under
oxidative conditions according to the present invention to a reducing
treatment with hydrogen prior to their use as catalysts in Fischer-Tropsch
type reactions.
The present invention further relates to a process for the
hydrodesulphurisation of hydrocarbonaceous materials by contacting such
materials in the presence of hydrogen at elevated temperature and pressure
with a catalyst comprising one or more catalytically active metal
components on a support which catalyst has been obtained by subjecting a
complex cyanide according to the general formula M.sub.1 M.sub.2
(CN).sub.p-x (Y).sub.x wherein M.sub.1 represents a cationic moiety
comprising one or more metal ions, NH.sub.4.sup.+ and/or one or more
quaternary ammonium ions, M.sub.2 forms part of the anionic moiety and
represents one or more polyvalent metals, CN represents a cyanide moiety
as defined hereinbefore, Y represents one or more ligands p is a number
ranging from 2-8, x is a number ranging from 0-4 and p/x is at least 1
when x>0, present on a carrier to a decomposition treatment under
oxidative conditions.
In particular, catalysts loaded with one or more Group VIb and/or Group
VIII metals, such as nickel, cobalt, molybdenum and cobalt can be suitably
applied in hydrodesulphurisation processes preferably when they are in
sulphided form. Suitably, a pre-sulphiding technique can be applied to the
metal oxides present on the appropriate carrier after the decomposition
treatment according to the present invention. It is also possible to apply
an in situ sulphidation technique. Normally, the catalysts used in
hydrodesulphurisation duty will also act as demetallisation catalysts
and/or denitrogenation catalysts depending on the feedstock to be treated.
The conditions to be applied in
hydrodesulphurisation/hydrodemetallisation/hydrodenitrification processes
are well known in the art and need not to be elucidated here.
The present invention also relates to a process for producing ethylene
oxide and/or ethylene glycol by using supported silver catalysts.
optionally containing one or more promoters, which silver catalysts have
been obtained from the appropriate complex cyanide which has been
subjected to a decomposition treatment according to the present invention.
The catalytic processes described hereinabove can be carried out suitably
by using catalysts which have been prepared from complex cyanides as
defined hereinbefore which have been subjected to a decomposition
treatment according to the present invention which has been carried out in
an environment containing at least 0.5% by volume of an oxidising agent at
a temperature of at least 200.degree. C. Preferably the decomposition
treatment is to be carried out using (diluted) air at a temperature
between 250.degree. C. and 450.degree. C.
Preferably, the process for preparing hydrocarbons and/or oxygenates is
carried out by using a catalyst obtainable from a complex cyanide wherein
M.sub.1 represents one or more of Group VIII. one or more of Group Ib or
one or more Group IVa metal moieties, M.sub.2 represents a Fe, Co, Ni, Mo
or W metal moiety, CN represents cyanide, p represents 4, 6 or 8 and x is
zero. In particular, catalysts are attractive which are obtainable from
complex cyanides wherein M.sub.1 represents a Cu, Ni or Co moiety and
M.sub.2 represents a Fe, W or Mo moiety.
Preferably, the process for hydrodesulphurising hydrocarbonaceous materials
is carried out by using a catalyst obtainable from a complex cyanide
wherein M.sub.1 represents one or more Group VIb and/or Group VIII metal
moieties, M.sub.2 represents a Co, Ni, Mo or W metal moiety. CN represents
cyanide, p represents 4, 6 or 8 and x is zero. In particular, catalysts
are attractive which are obtainable from complex cyanides wherein M.sub.1
represents a Ni and/or Co metal moiety and M.sub.2 represents a Mo and/or
W moiety. The present invention will now be illustrated by the following
Examples.
EXAMPLE 1
a) Preparation of complex cyanide
1. 2.50 grammes of Na.sub.2 Fe(CN).sub.5 NO.2H.sub.2 O were dissolved in
100 ml water and slowly injected into a solution of 2.02 grammes of
Cu(NO.sub.3).sub.2.3H.sub.2 O in 1000 ml water wherein 4.00 grammes of
Al.sub.2 O.sub.3 (Degussa Aluminum Oxid C) had been suspended. The pH of
the vigorously stirred suspension was 5.0 and the temperature was
22.degree. C. The resulting precipitate was suction-filtered, washed with
1000 ml water and vacuum dried. The product was pelletized, crushed and a
fraction of 0.43-0.71 mm of the Cu/Fe-complex cyanide was selected.
2. The experiment described in Example 1a)1 was repeated using the
appropriate amount of K.sub.4 Fe(CN).sub.6.3H.sub.2 O. After working up
the corresponding Cu.sub.2/ Fe-complex cyanide was obtained.
3. The experiment described in Example 1a)1 was repeated using the
appropriate amount of K.sub.3 Fe(CN).sub.6. After working up the
corresponding Cu.sub.3/ Fe.sub.2 -complex cyanide was obtained.
b) Decomposition of complex cyanide
1. 0.05 grammes of the complex cyanide prepared as described under a)1 were
placed in a thermobalance and heated at a rate of 5.degree. C./min up to
900.degree. C. in a flow of gas comprising 90% by volume of argon and 10%
by volume of hydrogen.
The rate of weight loss (dM/dt) and the composition of the gas phase as
monitored with a massspectrometer over the temperature interval are given
in FIG. Ia.
2. A similar amount of complex cyanide was subjected to the treatment
described in b)1 but using only argon as the gas flow The rate of weight
loss and the composition of the gas phase are given in FIG. Ib.
3. A similar amount of complex cyanide was subjected to the treatment
described in b)2 but using a gas comprising 90% by volume of argon and 10%
by volume of oxygen. The rate of weight loss and the composition of the
gas phase are given in FIG. Ic.
It will be clear that the decomposition under oxidative conditions in
accordance with the present invention (experiment b)3 FIG. Ic) not only
takes place at a substantially lower temperature than is required when a
thermal decomposition (experiment b)2) or a decomposition under reducing
conditions (experiment b)1) is envisaged but also is much more effective
in removing the cyanide moieties from the complex cyanide.
c) Reduction of decomposed cyanide
0.05 grammes of the complex cyanide prepared as described under a)1 were
heated at a rate of 5.degree. C./min up to 270.degree. C. in a flow of gas
comprising 99% by volume of helium and 1% by volume of oxygen and left for
24 hours. Thereafter, the sample was placed in a fixed-bed microreactor
and heated at a rate of 5.degree. C./min up to 900.degree. C. in a flow of
gas comprising 90% by volume of argon a volume of hydrogen. The hydrogen
consumption was measured with a Hot Wire Detector and depicted over the
temperature interval in FIG. II.
d) Physical characterisation of the metallic phases
The sizes of the metallic phases as determined by X-ray diffraction
line-broadening are summarised in Table 1.
TABLE 1
______________________________________
treatment
complex (nm)
Fe phase (nm)
Cu phase (nm)
______________________________________
a)1 41 -- --
b)1 -- 26 78
b)2 -- 33 116
b)3 -- 21 21
______________________________________
EXAMPLE 2
The experiment described in Example 1a)1 was repeated by dissolving 2.37
grammes of K.sub.4 Fe(CN).sub.6.3H.sub.2 O in 100 ml water and slowly
injecting the solution into a solution of 1.36 grammes of
Cu(NO.sub.3).sub.2 3H.sub.2 O and 1.63 grammes of
Ni(NO.sub.3).sub.2.bH.sub.2 O in 1000 ml water wherein 4.00 grammes of
Al.sub.2 O.sub.3 had been suspended. The pH of the vigorously stirred
suspension was 5.0 and the temperature was 22.degree. C. After working up
the corresponding Cu/Ni/Fe-complex cyanide was obtained.
EXAMPLE 3
The experiment described in Example 1a)1 was repeated by dissolving 0.87
grammes of K.sub.3 Fe(CN).sub.6 in 100 ml water and slowly injecting the
solution into a solution of 1.34 grammes of AgNO.sub.3 in 1000 ml water
wherein 4.00 grammes of Al.sub.2 O.sub.3 had been suspended. The pH of the
vigorously stirred suspension was 5.0 and the temperature was 22.degree.
C. After working up the corresponding Ag/Fe-complex cyanide was obtained.
EXAMPLE 4
The experiment described in Example 1a)1 was repeated by dissolving 2.55
grammes of K.sub.4 Fe(CN).sub.6.3H.sub.2 O in 100 ml water and slowly
injecting the solution into a solution of 3.03 grammes of
Mn(NO.sub.3).sub.2.4H.sub.2 O in 1000 ml water wherein 4.00 grammes of
Al.sub.2 O.sub.3 had been suspended. The pH of the vigorously stirred
suspension was 5.0 and the temperature was 22.degree. C. After working up
the corresponding Mn/Fe-complex cyanide was obtained.
EXAMPLE 5
The experiment described in Example 1a)1 was repeated by dissolving 2.32
grammes of K.sub.4 Mo(CN).sub.8.2H.sub.2 O in 100 ml water and slowly
injecting the solution into a solution of 2.72 grammes of
Co(NO.sub.3).sub.2.6H.sub.2 O in 1000 ml water wherein 4.00 grammes of
Al.sub.2 O.sub.3 had been suspended. The pH of the vigorously stirred
suspension was 5.0 and the temperature was 22.degree. C. After working up
the corresponding Co/Mo-complex cyanide was obtained.
EXAMPLE 6
The experiment described in Example 1a)1 was repeated by dissolving 2.39
grammes of K.sub.4 Mo(CN).sub.8.2H.sub.2 O in 100 ml water and slowly
injecting the solution into a solution of 1.92 grammes of
FeCl.sub.2.4H.sub.2 O in 1000 ml water wherein 4.00 grammes of Al.sub.2
O.sub.3 had been suspended. The pH of the vigorously stirred suspension
was 5.0 and the temperature was 22.degree. C. After working up the
corresponding Fe/Mo-complex cyanide was obtained.
EXAMPLE 7
The experiment described in Example 1a)1 was repeated by dissolving 1.89
grammes of K.sub.2 Pd(CN).sub.4.1H.sub.2 O in 100 ml water and slowly
injecting the solution into a solution of 1.23 grammes of
FeCl.sub.2.4H.sub.2 O in 1000 ml water wherein 4.00 grammes of Al.sub.2
O.sub.3 has been suspended. The pH of the vigorously stirred suspension
was 5.0 and the temperature was 22.degree. C. After working up the
corresponding Fe/Pd-complex cyanide was obtained.
EXAMPLE 8
Catalyst testing
The catalysts prepared as described in Examples 1a)1, 1a)2 and 1a)3 were
tested for the conversion of synthesis gas in a tubular reactor in which
the catalyst was operated in the form of a fixed bed with a bulk volume of
1.5 ml.
Prior to testing, the catalysts were reduced with hydrogen under the
following conditions: pressure 0.1 MPa; temperature: programmed heating
procedure during 64 hours from 100.degree. C. to 275.degree. C.; reduction
gas:argon/hydrogen 9:1.
The conditions during the conversion of synthesis gas were pressure 0.1
MPa; temperature 275.degree. C.; H.sub.2 /CO ratio: 2; GHSV: 0.35
Nl/1/min.
The three catalysts tested each showed an initial activity of about 90-135
mmol C/kg iron/s, and a steady state activity thereafter about 50 hours of
about 20 mmol C/kg iron/s. The catalyst prepared as described in Example
1a)1 showed the highest initial activity and the lowest steady state
activity, while the catalyst prepared as described in Example 1a)3 showed
the lowest initial activity but the highest steady state activity. From an
analysis of the hydrocarbons obtained during the steady state activity of
the catalysts it appeared that the Schulz-Flory numbers varied from about
0.4 (catalyst prepared as described in Example 1a)1) to 0.47.
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